Add NAT64 CLAT implementation as defined in RFC6877.

CLAT is customer-side translator that algorithmically translates 1:1
private IPv4 addresses to global IPv6 addresses, and vice versa.
It is implemented as part of ipfw_nat64 kernel module. When module
is loaded or compiled into the kernel, it registers "nat64clat" external
action. External action named instance can be created using `create`
command and then used in ipfw rules. The create command accepts two
IPv6 prefixes `plat_prefix` and `clat_prefix`. If plat_prefix is ommitted,
IPv6 NAT64 Well-Known prefix 64:ff9b::/96 will be used.

  # ipfw nat64clat CLAT create clat_prefix SRC_PFX plat_prefix DST_PFX
  # ipfw add nat64clat CLAT ip4 from IPv4_PFX to any out
  # ipfw add nat64clat CLAT ip6 from DST_PFX to SRC_PFX in

Obtained from:	Yandex LLC
Submitted by:	Boris N. Lytochkin
MFC after:	1 month
Relnotes:	yes
Sponsored by:	Yandex LLC

5 files changed, 932 insertions, 0 deletions

diff --git a/sys/netpfil/ipfw/nat64/ip_fw_nat64.c b/sys/netpfil/ipfw/nat64/ip_fw_nat64.c
index a0a975ac6b86..ea5ff597a7bf 100644
--- a/sys/netpfil/ipfw/nat64/ip_fw_nat64.c
+++ b/sys/netpfil/ipfw/nat64/ip_fw_nat64.c
@@ -86,9 +86,15 @@ vnet_ipfw_nat64_init(const void *arg __unused)
 	error = nat64stl_init(ch, first);
 	if (error != 0)
 		return (error);
+	error = nat64clat_init(ch, first);
+	if (error != 0) {
+		nat64stl_uninit(ch, first);
+		return (error);
+	}
 	error = nat64lsn_init(ch, first);
 	if (error != 0) {
 		nat64stl_uninit(ch, first);
+		nat64clat_uninit(ch, first);
 		return (error);
 	}
 	return (0);
@@ -103,6 +109,7 @@ vnet_ipfw_nat64_uninit(const void *arg __unused)
 	ch = &V_layer3_chain;
 	last = IS_DEFAULT_VNET(curvnet) ? 1: 0;
 	nat64stl_uninit(ch, last);
+	nat64clat_uninit(ch, last);
 	nat64lsn_uninit(ch, last);
 	return (0);
 }
diff --git a/sys/netpfil/ipfw/nat64/ip_fw_nat64.h b/sys/netpfil/ipfw/nat64/ip_fw_nat64.h
index 11b60b873675..d6f38405cfba 100644
--- a/sys/netpfil/ipfw/nat64/ip_fw_nat64.h
+++ b/sys/netpfil/ipfw/nat64/ip_fw_nat64.h
@@ -54,5 +54,7 @@ int	nat64stl_init(struct ip_fw_chain *ch, int first);
 void	nat64stl_uninit(struct ip_fw_chain *ch, int last);
 int	nat64lsn_init(struct ip_fw_chain *ch, int first);
 void	nat64lsn_uninit(struct ip_fw_chain *ch, int last);
+int	nat64clat_init(struct ip_fw_chain *ch, int first);
+void	nat64clat_uninit(struct ip_fw_chain *ch, int last);
 
 #endif /* _IP_FW_NAT64_H_ */
diff --git a/sys/netpfil/ipfw/nat64/nat64clat.c b/sys/netpfil/ipfw/nat64/nat64clat.c
new file mode 100644
index 000000000000..fcc922726d02
--- /dev/null
+++ b/sys/netpfil/ipfw/nat64/nat64clat.c
@@ -0,0 +1,255 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Yandex LLC
+ * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org>
+ * Copyright (c) 2019 Boris N. Lytochkin <lytboris@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/counter.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/mbuf.h>
+#include <sys/module.h>
+#include <sys/rmlock.h>
+#include <sys/rwlock.h>
+#include <sys/socket.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/if_pflog.h>
+#include <net/pfil.h>
+
+#include <netinet/in.h>
+#include <netinet/ip.h>
+#include <netinet/ip_icmp.h>
+#include <netinet/ip_var.h>
+#include <netinet/ip_fw.h>
+#include <netinet/ip6.h>
+#include <netinet/icmp6.h>
+#include <netinet6/ip_fw_nat64.h>
+
+#include <netpfil/ipfw/ip_fw_private.h>
+#include <netpfil/pf/pf.h>
+
+#include "nat64clat.h"
+
+#define	NAT64_LOOKUP(chain, cmd)	\
+	(struct nat64clat_cfg *)SRV_OBJECT((chain), (cmd)->arg1)
+
+static void
+nat64clat_log(struct pfloghdr *plog, struct mbuf *m, sa_family_t family,
+    uint32_t kidx)
+{
+	static uint32_t pktid = 0;
+
+	memset(plog, 0, sizeof(*plog));
+	plog->length = PFLOG_REAL_HDRLEN;
+	plog->af = family;
+	plog->action = PF_NAT;
+	plog->dir = PF_IN;
+	plog->rulenr = htonl(kidx);
+	pktid++;
+	plog->subrulenr = htonl(pktid);
+	plog->ruleset[0] = '\0';
+	strlcpy(plog->ifname, "NAT64CLAT", sizeof(plog->ifname));
+	ipfw_bpf_mtap2(plog, PFLOG_HDRLEN, m);
+}
+
+static int
+nat64clat_handle_ip4(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
+    struct mbuf *m)
+{
+	struct pfloghdr loghdr, *logdata;
+	struct in6_addr saddr, daddr;
+	struct ip *ip;
+
+	ip = mtod(m, struct ip*);
+	/* source address for CLAT may be private with no harm */
+	if (nat64_check_ip4(ip->ip_src.s_addr) != 0 ||
+	    nat64_check_ip4(ip->ip_dst.s_addr) != 0 ||
+	    nat64_check_private_ip4(&cfg->base, ip->ip_dst.s_addr) != 0)
+		return (NAT64SKIP);
+
+	memcpy(&saddr, &cfg->base.clat_prefix, sizeof(saddr));
+	nat64_embed_ip4(&saddr, cfg->base.clat_plen, ip->ip_src.s_addr);
+	memcpy(&daddr, &cfg->base.plat_prefix, sizeof(daddr));
+	nat64_embed_ip4(&daddr, cfg->base.plat_plen, ip->ip_dst.s_addr);
+	if (cfg->base.flags & NAT64_LOG) {
+		logdata = &loghdr;
+		nat64clat_log(logdata, m, AF_INET, cfg->no.kidx);
+	} else
+		logdata = NULL;
+	return (nat64_do_handle_ip4(m, &saddr, &daddr, 0, &cfg->base,
+	    logdata));
+}
+
+static int
+nat64clat_handle_ip6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
+    struct mbuf *m)
+{
+	struct pfloghdr loghdr, *logdata;
+	struct ip6_hdr *ip6;
+	uint32_t aaddr;
+
+	/*
+	 * NOTE: we expect ipfw_chk() did m_pullup() up to upper level
+	 * protocol's headers. Also we skip some checks, that ip6_input(),
+	 * ip6_forward(), ip6_fastfwd() and ipfw_chk() already did.
+	 */
+	ip6 = mtod(m, struct ip6_hdr *);
+	/* Check ip6_dst matches configured prefix */
+	if (memcmp(&ip6->ip6_dst, &cfg->base.clat_prefix,
+	    cfg->base.clat_plen / 8) != 0)
+		return (NAT64SKIP);
+	/* Check ip6_src matches configured prefix */
+	if (memcmp(&ip6->ip6_src, &cfg->base.plat_prefix,
+	    cfg->base.plat_plen / 8) != 0)
+		return (NAT64SKIP);
+
+	if (cfg->base.flags & NAT64_LOG) {
+		logdata = &loghdr;
+		nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx);
+	} else
+		logdata = NULL;
+
+	aaddr = nat64_extract_ip4(&ip6->ip6_src, cfg->base.plat_plen);
+	return (nat64_do_handle_ip6(m, aaddr, 0, &cfg->base, logdata));
+}
+
+static int
+nat64clat_handle_icmp6(struct ip_fw_chain *chain, struct nat64clat_cfg *cfg,
+    struct mbuf *m)
+{
+	struct pfloghdr loghdr, *logdata;
+	struct nat64_counters *stats;
+	struct ip6_hdr *ip6i;
+	struct icmp6_hdr *icmp6;
+	uint32_t daddr;
+	int hlen, proto;
+
+	hlen = 0;
+	stats = &cfg->base.stats;
+	proto = nat64_getlasthdr(m, &hlen);
+	if (proto != IPPROTO_ICMPV6) {
+		NAT64STAT_INC(stats, dropped);
+		return (NAT64MFREE);
+	}
+	icmp6 = mtodo(m, hlen);
+	switch (icmp6->icmp6_type) {
+	case ICMP6_DST_UNREACH:
+	case ICMP6_PACKET_TOO_BIG:
+	case ICMP6_TIME_EXCEED_TRANSIT:
+	case ICMP6_PARAM_PROB:
+		break;
+	default:
+		NAT64STAT_INC(stats, dropped);
+		return (NAT64MFREE);
+	}
+	hlen += sizeof(struct icmp6_hdr);
+	if (m->m_pkthdr.len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN) {
+		NAT64STAT_INC(stats, dropped);
+		return (NAT64MFREE);
+	}
+	if (m->m_len < hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN)
+		m = m_pullup(m, hlen + sizeof(struct ip6_hdr) + ICMP_MINLEN);
+	if (m == NULL) {
+		NAT64STAT_INC(stats, nomem);
+		return (NAT64RETURN);
+	}
+	/*
+	 * Use destination address from inner IPv6 header to determine
+	 * IPv4 mapped address.
+	 */
+	ip6i = mtodo(m, hlen);
+	daddr = nat64_extract_ip4(&ip6i->ip6_dst, cfg->base.clat_plen);
+	if (daddr == 0) {
+		NAT64STAT_INC(stats, dropped);
+		return (NAT64MFREE);
+	}
+	if (cfg->base.flags & NAT64_LOG) {
+		logdata = &loghdr;
+		nat64clat_log(logdata, m, AF_INET6, cfg->no.kidx);
+	} else
+		logdata = NULL;
+	return (nat64_handle_icmp6(m, 0, daddr, 0, &cfg->base, logdata));
+}
+
+int
+ipfw_nat64clat(struct ip_fw_chain *chain, struct ip_fw_args *args,
+    ipfw_insn *cmd, int *done)
+{
+	ipfw_insn *icmd;
+	struct nat64clat_cfg *cfg;
+	int ret;
+
+	IPFW_RLOCK_ASSERT(chain);
+
+	*done = 0; /* try next rule if not matched */
+	icmd = cmd + 1;
+	if (cmd->opcode != O_EXTERNAL_ACTION ||
+	    cmd->arg1 != V_nat64clat_eid ||
+	    icmd->opcode != O_EXTERNAL_INSTANCE ||
+	    (cfg = NAT64_LOOKUP(chain, icmd)) == NULL)
+		return (0);
+
+	switch (args->f_id.addr_type) {
+	case 4:
+		ret = nat64clat_handle_ip4(chain, cfg, args->m);
+		break;
+	case 6:
+		ret = nat64clat_handle_ip6(chain, cfg, args->m);
+		break;
+	default:
+		return (0);
+	}
+
+	if (ret == NAT64SKIP) {
+		/*
+		 * In case when packet is ICMPv6 message from an intermediate
+		 * router, the source address of message will not match the
+		 * addresses from configured prefixes.
+		 */
+		if (args->f_id.proto != IPPROTO_ICMPV6)
+			return (0);
+
+		ret = nat64clat_handle_icmp6(chain, cfg, args->m);
+	}
+
+	if (ret == NAT64SKIP)
+		return (0);
+
+	*done = 1; /* terminate the search */
+	if (ret == NAT64MFREE)
+		m_freem(args->m);
+
+	args->m = NULL;
+	return (IP_FW_NAT64);
+}
diff --git a/sys/netpfil/ipfw/nat64/nat64clat.h b/sys/netpfil/ipfw/nat64/nat64clat.h
new file mode 100644
index 000000000000..70ca5ce5beb6
--- /dev/null
+++ b/sys/netpfil/ipfw/nat64/nat64clat.h
@@ -0,0 +1,54 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Yandex LLC
+ * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org>
+ * Copyright (c) 2019 Boris N. Lytochkin <lytboris@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ *
+ * $FreeBSD$
+ */
+
+#ifndef	_IP_FW_NAT64CLAT_H_
+#define	_IP_FW_NAT64CLAT_H_
+
+#include "ip_fw_nat64.h"
+#include "nat64_translate.h"
+
+struct nat64clat_cfg {
+	struct named_object	no;
+
+	struct nat64_config	base;
+#define	NAT64CLAT_FLAGSMASK	\
+	(NAT64_LOG | NAT64_ALLOW_PRIVATE) /* flags to pass to userland */
+	char			name[64];
+};
+
+VNET_DECLARE(uint16_t, nat64clat_eid);
+#define	V_nat64clat_eid	VNET(nat64clat_eid)
+#define	IPFW_TLV_NAT64CLAT_NAME	IPFW_TLV_EACTION_NAME(V_nat64clat_eid)
+
+int ipfw_nat64clat(struct ip_fw_chain *chain, struct ip_fw_args *args,
+    ipfw_insn *cmd, int *done);
+
+#endif
diff --git a/sys/netpfil/ipfw/nat64/nat64clat_control.c b/sys/netpfil/ipfw/nat64/nat64clat_control.c
new file mode 100644
index 000000000000..2f6ac812bdd4
--- /dev/null
+++ b/sys/netpfil/ipfw/nat64/nat64clat_control.c
@@ -0,0 +1,614 @@
+/*-
+ * SPDX-License-Identifier: BSD-2-Clause-FreeBSD
+ *
+ * Copyright (c) 2019 Yandex LLC
+ * Copyright (c) 2019 Andrey V. Elsukov <ae@FreeBSD.org>
+ * Copyright (c) 2019 Boris N. Lytochkin <lytboris@gmail.com>
+ *
+ * Redistribution and use in source and binary forms, with or without
+ * modification, are permitted provided that the following conditions
+ * are met:
+ *
+ * 1. Redistributions of source code must retain the above copyright
+ *    notice, this list of conditions and the following disclaimer.
+ * 2. Redistributions in binary form must reproduce the above copyright
+ *    notice, this list of conditions and the following disclaimer in the
+ *    documentation and/or other materials provided with the distribution.
+ *
+ * THIS SOFTWARE IS PROVIDED BY THE AUTHOR ``AS IS'' AND ANY EXPRESS OR
+ * IMPLIED WARRANTIES, INCLUDING, BUT NOT LIMITED TO, THE IMPLIED WARRANTIES
+ * OF MERCHANTABILITY AND FITNESS FOR A PARTICULAR PURPOSE ARE DISCLAIMED.
+ * IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR ANY DIRECT, INDIRECT,
+ * INCIDENTAL, SPECIAL, EXEMPLARY, OR CONSEQUENTIAL DAMAGES (INCLUDING, BUT
+ * NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS OR SERVICES; LOSS OF USE,
+ * DATA, OR PROFITS; OR BUSINESS INTERRUPTION) HOWEVER CAUSED AND ON ANY
+ * THEORY OF LIABILITY, WHETHER IN CONTRACT, STRICT LIABILITY, OR TORT
+ * (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING IN ANY WAY OUT OF THE USE OF
+ * THIS SOFTWARE, EVEN IF ADVISED OF THE POSSIBILITY OF SUCH DAMAGE.
+ */
+
+#include <sys/cdefs.h>
+__FBSDID("$FreeBSD$");
+
+#include <sys/param.h>
+#include <sys/systm.h>
+#include <sys/counter.h>
+#include <sys/errno.h>
+#include <sys/kernel.h>
+#include <sys/lock.h>
+#include <sys/malloc.h>
+#include <sys/mbuf.h>
+#include <sys/module.h>
+#include <sys/rmlock.h>
+#include <sys/rwlock.h>
+#include <sys/socket.h>
+#include <sys/sockopt.h>
+#include <sys/syslog.h>
+#include <sys/sysctl.h>
+
+#include <net/if.h>
+#include <net/if_var.h>
+#include <net/route.h>
+#include <net/vnet.h>
+
+#include <netinet/in.h>
+#include <netinet/ip_var.h>
+#include <netinet/ip_fw.h>
+#include <netinet6/in6_var.h>
+#include <netinet6/ip6_var.h>
+#include <netinet6/ip_fw_nat64.h>
+
+#include <netpfil/ipfw/ip_fw_private.h>
+
+#include "nat64clat.h"
+
+VNET_DEFINE(uint16_t, nat64clat_eid) = 0;
+
+static struct nat64clat_cfg *nat64clat_alloc_config(const char *name,
+    uint8_t set);
+static void nat64clat_free_config(struct nat64clat_cfg *cfg);
+static struct nat64clat_cfg *nat64clat_find(struct namedobj_instance *ni,
+    const char *name, uint8_t set);
+
+static struct nat64clat_cfg *
+nat64clat_alloc_config(const char *name, uint8_t set)
+{
+	struct nat64clat_cfg *cfg;
+
+	cfg = malloc(sizeof(struct nat64clat_cfg), M_IPFW, M_WAITOK | M_ZERO);
+	COUNTER_ARRAY_ALLOC(cfg->base.stats.cnt, NAT64STATS, M_WAITOK);
+	cfg->no.name = cfg->name;
+	cfg->no.etlv = IPFW_TLV_NAT64CLAT_NAME;
+	cfg->no.set = set;
+	strlcpy(cfg->name, name, sizeof(cfg->name));
+	return (cfg);
+}
+
+static void
+nat64clat_free_config(struct nat64clat_cfg *cfg)
+{
+
+	COUNTER_ARRAY_FREE(cfg->base.stats.cnt, NAT64STATS);
+	free(cfg, M_IPFW);
+}
+
+static void
+nat64clat_export_config(struct ip_fw_chain *ch, struct nat64clat_cfg *cfg,
+    ipfw_nat64clat_cfg *uc)
+{
+	uc->plat_prefix = cfg->base.plat_prefix;
+	uc->plat_plen = cfg->base.plat_plen;
+	uc->clat_prefix = cfg->base.clat_prefix;
+	uc->clat_plen = cfg->base.clat_plen;
+	uc->flags = cfg->base.flags & NAT64CLAT_FLAGSMASK;
+	uc->set = cfg->no.set;
+	strlcpy(uc->name, cfg->no.name, sizeof(uc->name));
+}
+
+struct nat64clat_dump_arg {
+	struct ip_fw_chain *ch;
+	struct sockopt_data *sd;
+};
+
+static int
+export_config_cb(struct namedobj_instance *ni, struct named_object *no,
+    void *arg)
+{
+	struct nat64clat_dump_arg *da = (struct nat64clat_dump_arg *)arg;
+	ipfw_nat64clat_cfg *uc;
+
+	uc = (ipfw_nat64clat_cfg *)ipfw_get_sopt_space(da->sd, sizeof(*uc));
+	nat64clat_export_config(da->ch, (struct nat64clat_cfg *)no, uc);
+	return (0);
+}
+
+static struct nat64clat_cfg *
+nat64clat_find(struct namedobj_instance *ni, const char *name, uint8_t set)
+{
+	struct nat64clat_cfg *cfg;
+
+	cfg = (struct nat64clat_cfg *)ipfw_objhash_lookup_name_type(ni, set,
+	    IPFW_TLV_NAT64CLAT_NAME, name);
+
+	return (cfg);
+}
+
+/*
+ * Creates new consumer-side nat64 translator instance.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_lheader ipfw_nat64clat_cfg ]
+ *
+ * Returns 0 on success
+ */
+static int
+nat64clat_create(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
+    struct sockopt_data *sd)
+{
+	ipfw_obj_lheader *olh;
+	ipfw_nat64clat_cfg *uc;
+	struct namedobj_instance *ni;
+	struct nat64clat_cfg *cfg;
+
+	if (sd->valsize != sizeof(*olh) + sizeof(*uc))
+		return (EINVAL);
+
+	olh = (ipfw_obj_lheader *)sd->kbuf;
+	uc = (ipfw_nat64clat_cfg *)(olh + 1);
+
+	if (ipfw_check_object_name_generic(uc->name) != 0)
+		return (EINVAL);
+
+	if (uc->set >= IPFW_MAX_SETS ||
+	    nat64_check_prefix6(&uc->plat_prefix, uc->plat_plen) != 0 ||
+	    nat64_check_prefix6(&uc->clat_prefix, uc->clat_plen) != 0)
+		return (EINVAL);
+
+	ni = CHAIN_TO_SRV(ch);
+
+	IPFW_UH_RLOCK(ch);
+	if (nat64clat_find(ni, uc->name, uc->set) != NULL) {
+		IPFW_UH_RUNLOCK(ch);
+		return (EEXIST);
+	}
+	IPFW_UH_RUNLOCK(ch);
+
+	cfg = nat64clat_alloc_config(uc->name, uc->set);
+	cfg->base.plat_prefix = uc->plat_prefix;
+	cfg->base.plat_plen = uc->plat_plen;
+	cfg->base.clat_prefix = uc->clat_prefix;
+	cfg->base.clat_plen = uc->clat_plen;
+	cfg->base.flags = (uc->flags & NAT64CLAT_FLAGSMASK) |
+	    NAT64_CLATPFX | NAT64_PLATPFX;
+	if (IN6_IS_ADDR_WKPFX(&cfg->base.plat_prefix))
+		cfg->base.flags |= NAT64_WKPFX;
+
+	IPFW_UH_WLOCK(ch);
+
+	if (nat64clat_find(ni, uc->name, uc->set) != NULL) {
+		IPFW_UH_WUNLOCK(ch);
+		nat64clat_free_config(cfg);
+		return (EEXIST);
+	}
+
+	if (ipfw_objhash_alloc_idx(ni, &cfg->no.kidx) != 0) {
+		IPFW_UH_WUNLOCK(ch);
+		nat64clat_free_config(cfg);
+		return (ENOSPC);
+	}
+	ipfw_objhash_add(CHAIN_TO_SRV(ch), &cfg->no);
+	/* Okay, let's link data */
+	SRV_OBJECT(ch, cfg->no.kidx) = cfg;
+	IPFW_UH_WUNLOCK(ch);
+
+	return (0);
+}
+
+/*
+ * Change existing nat64clat instance configuration.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ipfw_nat64clat_cfg ]
+ * Reply: [ ipfw_obj_header ipfw_nat64clat_cfg ]
+ *
+ * Returns 0 on success
+ */
+static int
+nat64clat_config(struct ip_fw_chain *ch, ip_fw3_opheader *op,
+    struct sockopt_data *sd)
+{
+	ipfw_obj_header *oh;
+	ipfw_nat64clat_cfg *uc;
+	struct nat64clat_cfg *cfg;
+	struct namedobj_instance *ni;
+	uint32_t flags;
+
+	if (sd->valsize != sizeof(*oh) + sizeof(*uc))
+		return (EINVAL);
+
+	oh = (ipfw_obj_header *)ipfw_get_sopt_space(sd,
+	    sizeof(*oh) + sizeof(*uc));
+	uc = (ipfw_nat64clat_cfg *)(oh + 1);
+
+	if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
+	    oh->ntlv.set >= IPFW_MAX_SETS)
+		return (EINVAL);
+
+	ni = CHAIN_TO_SRV(ch);
+	if (sd->sopt->sopt_dir == SOPT_GET) {
+		IPFW_UH_RLOCK(ch);
+		cfg = nat64clat_find(ni, oh->ntlv.name, oh->ntlv.set);
+		if (cfg == NULL) {
+			IPFW_UH_RUNLOCK(ch);
+			return (ENOENT);
+		}
+		nat64clat_export_config(ch, cfg, uc);
+		IPFW_UH_RUNLOCK(ch);
+		return (0);
+	}
+
+	IPFW_UH_WLOCK(ch);
+	cfg = nat64clat_find(ni, oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_WUNLOCK(ch);
+		return (ENOENT);
+	}
+
+	/*
+	 * For now allow to change only following values:
+	 *  plat_prefix, plat_plen, clat_prefix, clat_plen, flags.
+	 */
+	flags = 0;
+	if (uc->plat_plen != cfg->base.plat_plen ||
+	    !IN6_ARE_ADDR_EQUAL(&uc->plat_prefix, &cfg->base.plat_prefix)) {
+		if (nat64_check_prefix6(&uc->plat_prefix, uc->plat_plen) != 0) {
+			IPFW_UH_WUNLOCK(ch);
+			return (EINVAL);
+		}
+		flags |= NAT64_PLATPFX;
+	}
+
+	if (uc->clat_plen != cfg->base.clat_plen ||
+	    !IN6_ARE_ADDR_EQUAL(&uc->clat_prefix, &cfg->base.clat_prefix)) {
+		if (nat64_check_prefix6(&uc->clat_prefix, uc->clat_plen) != 0) {
+			IPFW_UH_WUNLOCK(ch);
+			return (EINVAL);
+		}
+		flags |= NAT64_CLATPFX;
+	}
+
+	if (flags != 0) {
+		IPFW_WLOCK(ch);
+		if (flags & NAT64_PLATPFX) {
+			cfg->base.plat_prefix = uc->plat_prefix;
+			cfg->base.plat_plen = uc->plat_plen;
+		}
+		if (flags & NAT64_CLATPFX) {
+			cfg->base.clat_prefix = uc->clat_prefix;
+			cfg->base.clat_plen = uc->clat_plen;
+		}
+		IPFW_WUNLOCK(ch);
+	}
+
+	cfg->base.flags &= ~NAT64CLAT_FLAGSMASK;
+	cfg->base.flags |= uc->flags & NAT64CLAT_FLAGSMASK;
+
+	IPFW_UH_WUNLOCK(ch);
+	return (0);
+}
+
+static void
+nat64clat_detach_config(struct ip_fw_chain *ch, struct nat64clat_cfg *cfg)
+{
+
+	IPFW_UH_WLOCK_ASSERT(ch);
+
+	ipfw_objhash_del(CHAIN_TO_SRV(ch), &cfg->no);
+	ipfw_objhash_free_idx(CHAIN_TO_SRV(ch), cfg->no.kidx);
+}
+
+/*
+ * Destroys nat64 instance.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ]
+ *
+ * Returns 0 on success
+ */
+static int
+nat64clat_destroy(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
+    struct sockopt_data *sd)
+{
+	ipfw_obj_header *oh;
+	struct nat64clat_cfg *cfg;
+
+	if (sd->valsize != sizeof(*oh))
+		return (EINVAL);
+
+	oh = (ipfw_obj_header *)sd->kbuf;
+	if (ipfw_check_object_name_generic(oh->ntlv.name) != 0)
+		return (EINVAL);
+
+	IPFW_UH_WLOCK(ch);
+	cfg = nat64clat_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_WUNLOCK(ch);
+		return (ENOENT);
+	}
+	if (cfg->no.refcnt > 0) {
+		IPFW_UH_WUNLOCK(ch);
+		return (EBUSY);
+	}
+
+	ipfw_reset_eaction_instance(ch, V_nat64clat_eid, cfg->no.kidx);
+	SRV_OBJECT(ch, cfg->no.kidx) = NULL;
+	nat64clat_detach_config(ch, cfg);
+	IPFW_UH_WUNLOCK(ch);
+
+	nat64clat_free_config(cfg);
+	return (0);
+}
+
+/*
+ * Lists all nat64clat instances currently available in kernel.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_lheader ]
+ * Reply: [ ipfw_obj_lheader ipfw_nat64clat_cfg x N ]
+ *
+ * Returns 0 on success
+ */
+static int
+nat64clat_list(struct ip_fw_chain *ch, ip_fw3_opheader *op3,
+    struct sockopt_data *sd)
+{
+	ipfw_obj_lheader *olh;
+	struct nat64clat_dump_arg da;
+
+	/* Check minimum header size */
+	if (sd->valsize < sizeof(ipfw_obj_lheader))
+		return (EINVAL);
+
+	olh = (ipfw_obj_lheader *)ipfw_get_sopt_header(sd, sizeof(*olh));
+
+	IPFW_UH_RLOCK(ch);
+	olh->count = ipfw_objhash_count_type(CHAIN_TO_SRV(ch),
+	    IPFW_TLV_NAT64CLAT_NAME);
+	olh->objsize = sizeof(ipfw_nat64clat_cfg);
+	olh->size = sizeof(*olh) + olh->count * olh->objsize;
+
+	if (sd->valsize < olh->size) {
+		IPFW_UH_RUNLOCK(ch);
+		return (ENOMEM);
+	}
+	memset(&da, 0, sizeof(da));
+	da.ch = ch;
+	da.sd = sd;
+	ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), export_config_cb,
+	    &da, IPFW_TLV_NAT64CLAT_NAME);
+	IPFW_UH_RUNLOCK(ch);
+
+	return (0);
+}
+
+#define	__COPY_STAT_FIELD(_cfg, _stats, _field)	\
+	(_stats)->_field = NAT64STAT_FETCH(&(_cfg)->base.stats, _field)
+static void
+export_stats(struct ip_fw_chain *ch, struct nat64clat_cfg *cfg,
+    struct ipfw_nat64clat_stats *stats)
+{
+
+	__COPY_STAT_FIELD(cfg, stats, opcnt64);
+	__COPY_STAT_FIELD(cfg, stats, opcnt46);
+	__COPY_STAT_FIELD(cfg, stats, ofrags);
+	__COPY_STAT_FIELD(cfg, stats, ifrags);
+	__COPY_STAT_FIELD(cfg, stats, oerrors);
+	__COPY_STAT_FIELD(cfg, stats, noroute4);
+	__COPY_STAT_FIELD(cfg, stats, noroute6);
+	__COPY_STAT_FIELD(cfg, stats, noproto);
+	__COPY_STAT_FIELD(cfg, stats, nomem);
+	__COPY_STAT_FIELD(cfg, stats, dropped);
+}
+
+/*
+ * Get nat64clat statistics.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ]
+ * Reply: [ ipfw_obj_header ipfw_obj_ctlv [ uint64_t x N ]]
+ *
+ * Returns 0 on success
+ */
+static int
+nat64clat_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
+    struct sockopt_data *sd)
+{
+	struct ipfw_nat64clat_stats stats;
+	struct nat64clat_cfg *cfg;
+	ipfw_obj_header *oh;
+	ipfw_obj_ctlv *ctlv;
+	size_t sz;
+
+	sz = sizeof(ipfw_obj_header) + sizeof(ipfw_obj_ctlv) + sizeof(stats);
+	if (sd->valsize % sizeof(uint64_t))
+		return (EINVAL);
+	if (sd->valsize < sz)
+		return (ENOMEM);
+	oh = (ipfw_obj_header *)ipfw_get_sopt_header(sd, sz);
+	if (oh == NULL)
+		return (EINVAL);
+	memset(&stats, 0, sizeof(stats));
+
+	IPFW_UH_RLOCK(ch);
+	cfg = nat64clat_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_RUNLOCK(ch);
+		return (ENOENT);
+	}
+	export_stats(ch, cfg, &stats);
+	IPFW_UH_RUNLOCK(ch);
+
+	ctlv = (ipfw_obj_ctlv *)(oh + 1);
+	memset(ctlv, 0, sizeof(*ctlv));
+	ctlv->head.type = IPFW_TLV_COUNTERS;
+	ctlv->head.length = sz - sizeof(ipfw_obj_header);
+	ctlv->count = sizeof(stats) / sizeof(uint64_t);
+	ctlv->objsize = sizeof(uint64_t);
+	ctlv->version = IPFW_NAT64_VERSION;
+	memcpy(ctlv + 1, &stats, sizeof(stats));
+	return (0);
+}
+
+/*
+ * Reset nat64clat statistics.
+ * Data layout (v0)(current):
+ * Request: [ ipfw_obj_header ]
+ *
+ * Returns 0 on success
+ */
+static int
+nat64clat_reset_stats(struct ip_fw_chain *ch, ip_fw3_opheader *op,
+    struct sockopt_data *sd)
+{
+	struct nat64clat_cfg *cfg;
+	ipfw_obj_header *oh;
+
+	if (sd->valsize != sizeof(*oh))
+		return (EINVAL);
+	oh = (ipfw_obj_header *)sd->kbuf;
+	if (ipfw_check_object_name_generic(oh->ntlv.name) != 0 ||
+	    oh->ntlv.set >= IPFW_MAX_SETS)
+		return (EINVAL);
+
+	IPFW_UH_WLOCK(ch);
+	cfg = nat64clat_find(CHAIN_TO_SRV(ch), oh->ntlv.name, oh->ntlv.set);
+	if (cfg == NULL) {
+		IPFW_UH_WUNLOCK(ch);
+		return (ENOENT);
+	}
+	COUNTER_ARRAY_ZERO(cfg->base.stats.cnt, NAT64STATS);
+	IPFW_UH_WUNLOCK(ch);
+	return (0);
+}
+
+static struct ipfw_sopt_handler	scodes[] = {
+
+	{ IP_FW_NAT64CLAT_CREATE, 0,	HDIR_SET,	nat64clat_create },
+	{ IP_FW_NAT64CLAT_DESTROY,0,	HDIR_SET,	nat64clat_destroy },
+	{ IP_FW_NAT64CLAT_CONFIG, 0,	HDIR_BOTH,	nat64clat_config },
+	{ IP_FW_NAT64CLAT_LIST,   0,	HDIR_GET,	nat64clat_list },
+	{ IP_FW_NAT64CLAT_STATS,  0,	HDIR_GET,	nat64clat_stats },
+	{ IP_FW_NAT64CLAT_RESET_STATS,0,	HDIR_SET,	nat64clat_reset_stats },
+};
+
+static int
+nat64clat_classify(ipfw_insn *cmd, uint16_t *puidx, uint8_t *ptype)
+{
+	ipfw_insn *icmd;
+
+	icmd = cmd - 1;
+	if (icmd->opcode != O_EXTERNAL_ACTION ||
+	    icmd->arg1 != V_nat64clat_eid)
+		return (1);
+
+	*puidx = cmd->arg1;
+	*ptype = 0;
+	return (0);
+}
+
+static void
+nat64clat_update_arg1(ipfw_insn *cmd, uint16_t idx)
+{
+
+	cmd->arg1 = idx;
+}
+
+static int
+nat64clat_findbyname(struct ip_fw_chain *ch, struct tid_info *ti,
+    struct named_object **pno)
+{
+	int err;
+
+	err = ipfw_objhash_find_type(CHAIN_TO_SRV(ch), ti,
+	    IPFW_TLV_NAT64CLAT_NAME, pno);
+	return (err);
+}
+
+static struct named_object *
+nat64clat_findbykidx(struct ip_fw_chain *ch, uint16_t idx)
+{
+	struct namedobj_instance *ni;
+	struct named_object *no;
+
+	IPFW_UH_WLOCK_ASSERT(ch);
+	ni = CHAIN_TO_SRV(ch);
+	no = ipfw_objhash_lookup_kidx(ni, idx);
+	KASSERT(no != NULL, ("NAT with index %d not found", idx));
+
+	return (no);
+}
+
+static int
+nat64clat_manage_sets(struct ip_fw_chain *ch, uint16_t set, uint8_t new_set,
+    enum ipfw_sets_cmd cmd)
+{
+
+	return (ipfw_obj_manage_sets(CHAIN_TO_SRV(ch), IPFW_TLV_NAT64CLAT_NAME,
+	    set, new_set, cmd));
+}
+
+static struct opcode_obj_rewrite opcodes[] = {
+	{
+		.opcode = O_EXTERNAL_INSTANCE,
+		.etlv = IPFW_TLV_EACTION /* just show it isn't table */,
+		.classifier = nat64clat_classify,
+		.update = nat64clat_update_arg1,
+		.find_byname = nat64clat_findbyname,
+		.find_bykidx = nat64clat_findbykidx,
+		.manage_sets = nat64clat_manage_sets,
+	},
+};
+
+static int
+destroy_config_cb(struct namedobj_instance *ni, struct named_object *no,
+    void *arg)
+{
+	struct nat64clat_cfg *cfg;
+	struct ip_fw_chain *ch;
+
+	ch = (struct ip_fw_chain *)arg;
+	cfg = (struct nat64clat_cfg *)SRV_OBJECT(ch, no->kidx);
+	SRV_OBJECT(ch, no->kidx) = NULL;
+	nat64clat_detach_config(ch, cfg);
+	nat64clat_free_config(cfg);
+	return (0);
+}
+
+int
+nat64clat_init(struct ip_fw_chain *ch, int first)
+{
+
+	V_nat64clat_eid = ipfw_add_eaction(ch, ipfw_nat64clat, "nat64clat");
+	if (V_nat64clat_eid == 0)
+		return (ENXIO);
+	IPFW_ADD_SOPT_HANDLER(first, scodes);
+	IPFW_ADD_OBJ_REWRITER(first, opcodes);
+	return (0);
+}
+
+void
+nat64clat_uninit(struct ip_fw_chain *ch, int last)
+{
+
+	IPFW_DEL_OBJ_REWRITER(last, opcodes);
+	IPFW_DEL_SOPT_HANDLER(last, scodes);
+	ipfw_del_eaction(ch, V_nat64clat_eid);
+	/*
+	 * Since we already have deregistered external action,
+	 * our named objects become unaccessible via rules, because
+	 * all rules were truncated by ipfw_del_eaction().
+	 * So, we can unlink and destroy our named objects without holding
+	 * IPFW_WLOCK().
+	 */
+	IPFW_UH_WLOCK(ch);
+	ipfw_objhash_foreach_type(CHAIN_TO_SRV(ch), destroy_config_cb, ch,
+	    IPFW_TLV_NAT64CLAT_NAME);
+	V_nat64clat_eid = 0;
+	IPFW_UH_WUNLOCK(ch);
+}
+